On Wednesday, February 17, 2016 at 7:38:10 AM UTC-5, wrote:
During dry sanding isocyanates will be released, regardless how old the paint is. The newer the paint the more isocyanates will be released. You risk developing asthma, not really good for pilots . PPG Concept is a great paint but it requires proper precautions.
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Can someone confirm this? I understand the dangers while polyurethane is
being sprayed, and perhaps also in the early stages of curing. But I
thought the material was pretty much inert after it cured. I haven't
been able to find any warnings beyond the spraying process on the
internet. Can somebody supply more information? I'd like to be as
safe as possible. Or at last understand the dangers.

Jim Beckman

Jim, the release of isocyanates is caused by heat from sanding. The higher the heat the more isocyanates will be released. The amounts we are talking about are not large but almost all of us have been exposed to isocyanates over our lifetime and the effects of this chemical are cumulative so it is wise to avoid it as much as possible. If you use water you are generating very little heat plus isocyanates bind to water which is a plus in this case.

There are paint out there that are water based and since isocyanates bind to water they are much safer to use. Isocyanates will always seek water molecules to bind to so if you spray make sure you use full body cover.

PPG Concept for example can be painted with a roller or brush and then wet sanded like gel coat. It is very easy to repair single stage AU.

Wet sanding is the way to go (don't save on water) and if you sand dry do it very slowly and play really slow music

If you like to read here is the science http://www.pubfacts.com/detail/16434...paint-in-body-